The present invention relates to methods and apparatus for generating signals as writing or drawing is carried out, the signals being dependent on the way in which the writing or drawing is carried out.
Signature verification methods are known in which the dynamic characteristics of the signature (characteristics obtained while the signature is being written) are used in signature verification. The present invention is expected to be particularly useful in such signature verification systems, these systems being of application to monetary transfers and data entry, for example.
Apparatus for identifying characteristics of handwriting by moving a pen across a ridged writing surface is described in U.S. Pat. No. 4,122,435 and similar apparatus for signature verification is described in U.S. Pat. No. 3,955,178. The same principle is used in the signature verifier described in the IBM Technical Disclosure Bulletin, Volume 18, No. 7, Dec. 1975. A disadvantage of this method is the complexity of equipment required to sense the vibrations set up when the pen crosses a groove.
A known alternative which also suffers from the disadvantage of complexity is passing electrical signals into a grid of electrical conductors, the signals being representative in some way of the position of a conductor in the grid, and sensing signals using a pen whose position is to be determined. An example of such apparatus is described in U.S. Pat. No. 4,560,830. Other alternatives are described in European Patent Specifications 0132241 and 0035036.
According to a first aspect of the present invention there is provided a method of obtaining information as writing or drawing is carried out. comprising the steps of writing or drawing in relation to a surface marked in a predetermined way using a tip of an instrument which causes a trail to be left which can be traced later,
continually sensing for the tip crossing any of the marks, the sensing being carried out electromagnetically, and
analyzing the mark crossings on a temporal basis.
The main advantages of this method are that a visual trace of any writing carried out is left so that, if necessary, it can be checked later by eye; and that temporal analysis allows the writing instrument, processor and paperwork to be simple and inexpensive. Temporal analysis also has advantages as far as signature recognition is concerned: the dynamic features of a signature can be recognized and the signature cannot usually be reconstructed.
The surface may be marked by projecting light to provide light and dark areas forming a predetermined arrangement of marks on to the said surface. Thus the surface may be unmarked until the light and dark areas are projected on to it for example by projecting an image or partially masking the light, and remains marked only while light projection continues.
Sensing may be carried out by receiving electromagnetic radiation, visible or invisible, which is modulated when a said mark is crossed. The modulation may, for example. occur either by interruption if light is transmitted through the surface, or by reflection if light is reflected from the surface. Alternatively sensing may be carried out by electromagnetic induction when the lines are formed by material which has substantial magnetic properties and the instrument contains means for detecting such material.
Radiation sensed may be used to derive a representative signal in the writing instrument, or the radiation may be transmitted by way of an optical fiber, for example, to a sensor elsewhere.
The tip may be out of contact with the surface when writing or drawing is carried out but preferably it is in contact with the surface and cooperates with the surface to leave a trail which can be traced later. To this end the tip may dispense ink or a pencil lead type material (either of which can be visible or invisible) or the surface may be such that the tip marks the paper either visibly or invisibly, for example by the use of paper containing material which is released when pressure is applied. conventional carbon paper or similar papers or by the use of a surface such as, or similar to, slate or wax which is marked by the tip.
Where ink or a pencil lead like substance is used and sensing mark crossings depends on receiving electromagnetic radiation, either any ink or pencil-like substance chosen is transparent or translucent to the radiation but not to the marks on the surface, or the light receiver is positioned to prevent the radiation received being substantially interrupted by ink or a pencil lead-type substance dispensed by the tip.
Where ink is used which is not visible in ambient light, it may be of the type which can be seen in electromagnetic radiation of appropriate wavelength or of a type which can be developed by application of a suitable developer or by heating.
The marks on the surface may or may not be visible depending, for example on their position or on the wavelengths of light interrupted by crossing the marks. The marks may be lines and when lines are used there is preferably at least one set of the said lines in which the lines are parallel to one another.
In another example of the invention the writing instrument may contain as before, a light sensitive device but the surface may be illuminated by light having a particular wavelength either from above or below so reducing spurious modulation of ambient light received in sensing mark crossings. As an alternative in overcoming spurious modulation, light from the source may be chopped at a particular frequency and the light sensitive device may include a filter to extract a signal at this frequency.
In an alternative embodiment the writing instrument may contain a light source and the surface, except for the marks, may be transparent or translucent to the light, and the method then including receiving light passed from the writing instrument through the surface, or reflected from the surface, while writing or drawing is carried out.
According to a second aspect of the present invention there is provided a writing instrument comprising
a tip for the instrument which interacts with a surface on which writing or drawing is carried out to allow the path of the instrument to be traced after the instrument has been removed, and
a light source and/or light sensitive device, for transmitting or receiving light from the surface at the point where the said tip makes contact with the surface.
An advantage of such a writing instrument is that since light is transmitted or received where the tip makes contact, accurate data sensing results because there is no displacement or parallax between the sensing point and the tip.
Preferably the tip is formed by a spherical transparent ball point, such as glass, or suitable gem-stone material, which forms a convex-convex lens which greatly enhances light pick up at the point of contact. The instrument may then include a light guide between the ball point and the light sensitive device.
The tip may dispense an ink or equivalent as described above or it may be suitable for marking a surface by indentation or by releasing material in, or under, the surface.
The writing instrument may contain a circuit connected to the light sensitive device for storing and/or analyzing signals received from the light sensitive device. Where signals are stored the instrument may include means for transmitting signals to a receiver when predetermined actions have been completed by a user, for example either periodically or when an item of writing such as a signature has been completed. The means for transmitting signals may include electrodes adapted to make contact with an interface when the instrument is placed in a certain position or the interface may, for example, employ electromagnetic or ultrasonic coupling. Alternatively signals from the light sensitive device may, after storage, or during generation, be passed from the writing instrument to an analyzer by way of a connection or by way of a sonic or ultrasonic link or by way of a radiative link employing, for example, infra-red signals or radio signals.
Means (separate from the light sensitive device) for receiving signals may also be included in the writing instrument to allow information held by the instrument to be updated. The updated information may be displayed by the instrument and updating may be subject to satisfactory signature or other validation.
Information for display or to reprogram the analyzing circuit may be passed to the instrument by modulating light from a source which illuminates the writing or drawing surface.
In addition the writing instrument may contain means for indicating the result of analysis carried out by the circuit contained by the pen and/or means for manually changing operations carried out by the circuit.
The circuit may be programmed and/or constructed to allow changes in function to be carried out by means of signals transmitted by light by way of the tip. Such signals may be generated by recognition by the pen of characters written or by sweeping the pen over a pattern of lines, for example a bar code.
The writing instrument may have a reservoir for ink and a valve for allowing ink to flow over the tip from the reservoir when pressure is applied to the tip.
According to a third aspect of the present invention there is provided apparatus for use in obtaining information when writing or drawing is carried out using a writing instrument which transmits electromagnetic radiation through a writing tip, the apparatus comprising
a surface on which writing or drawing can be carried out or on which material for writing or drawing can be placed, and
means for receiving light from the said tip either by way of reflection from the surface or from material placed on the surface, or by transmission through the surface or the said material, the surface containing marks which are at least partially opaque to light from the tip if the surface is intended for writing or drawing.
Preferably, in this form of the invention, the surface is transparent or translucent and the light sensitive device is positioned at the side of a sheet forming the surface or below the said surface where it can receive light from substantially the whole of the area containing the said marks.
According to a fourth aspect of the present invention there is provided a method of analyzing drawing or writing comprising
using an instrument to draw or write on a marked surface.
deriving, within the instrument, a signal indicative of the occurrence of mark crossings while drawing or writing is carried out, and
analyzing the said signal.
According to a fifth aspect of the present invention there is provided a writing instrument comprising
means for sensing mark crossings made by a tip of the instrument on a marked surface, and
means for deriving a signal representative of the said crossings.
As with the first aspect of the invention the surface may be marked for the fourth and fifth aspects by projecting light to provide light and dark areas.
The invention includes apparatus corresponding to the method of the fourth aspect of the invention and methods corresponding to the fifth aspect.